Formal charge is the apparent electronic charge of each atom in a molecule based on the electron dot structure. Formal charge can be used to help in the assessment of resonance structure. Charge on the molecule or ion is equal to sum of all the formal charges. X= Number of valence electrons in a free atom Y= Number of unshared electrons on the atom Z= Number of bonds on the atom Formal charge = (X) -(Y)-(Z))Find formal charge on sulphur and nitrogen atom in :Which of the following is +1 in NO3- ion? What is the formal charge (average) on oxygen in CO32-?